format-du-output

<?php

$files = [];

// Get each line of input representing a file.
while($line = fgets(STDIN)) {
    $parts = explode("\t", trim($line));

    $files[] = [
        'size' => $parts[0],
        'name' => $parts[1],
    ];
}

// Sort the files by their size in descending order
usort($files, function ($first, $second) {
    return $second['size'] <=> $first['size'];
});

$maxLength = 0;

// Format the file size with comma as thousands separator
// and find the maximum size length.
foreach($files as $i => &$file) {
    $file['size'] = number_format($file['size'] * 1024);

    $length = strlen($file['size']);
    if($length > $maxLength) {
        $maxLength = $length;
    }
}
// Deallocate the $file variable reference to prevent unexpected behaviour.
unset($file);

// Align the size to the right by adding leading spaces and print the output.
foreach($files as $i => $file) {
    $size = str_pad($file['size'], $maxLength, ' ', STR_PAD_LEFT);
    echo "$size {$file['name']}\n";
}